81758328517 has 2 divisors, whose sum is σ = 81758328518. Its totient is φ = 81758328516.

The previous prime is 81758328473. The next prime is 81758328521. The reversal of 81758328517 is 71582385718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73557033796 + 8201294721 = 271214^2 + 90561^2 .

It is a cyclic number.

It is not a de Polignac number, because 81758328517 - 2³¹ = 79610844869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81758328527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40879164258 + 40879164259.

It is an arithmetic number, because the mean of its divisors is an integer number (40879164259).

Almost surely, 2^81758328517 is an apocalyptic number.

It is an amenable number.

81758328517 is a deficient number, since it is larger than the sum of its proper divisors (1).

81758328517 is an equidigital number, since it uses as much as digits as its factorization.

81758328517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3763200, while the sum is 55.

The spelling of 81758328517 in words is "eighty-one billion, seven hundred fifty-eight million, three hundred twenty-eight thousand, five hundred seventeen".